[PATCH v2 1/6] staging: wfx: fix init/remove vs IRQ race

[MichaÅ MirosÅaw]

Current code races in init/exit with interrupt handlers. This is noticed
by the warning below. Fix it by using devres for ordering allocations and
IRQ de/registration.

WARNING: CPU: 0 PID: 827 at drivers/staging/wfx/bus_spi.c:142 wfx_spi_irq_handler+0x5c/0x64 [wfx]
race condition in driver init/deinit

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 0096214a59a7 ("staging: wfx: add support for I/O access")
Signed-off-by: MichaÅ MirosÅaw <mirq-linux@xxxxxxxxxxxx>
---
v2: use devres to fix the races
---
 drivers/staging/wfx/bus_sdio.c | 15 ++++++---------
 drivers/staging/wfx/bus_spi.c  | 27 ++++++++++++++-------------
 drivers/staging/wfx/main.c     | 21 +++++++++++++--------
 drivers/staging/wfx/main.h     |  1 -
 4 files changed, 33 insertions(+), 31 deletions(-)

diff --git a/drivers/staging/wfx/bus_sdio.c b/drivers/staging/wfx/bus_sdio.c
index f8901164c206..5450bd5e1b5d 100644
--- a/drivers/staging/wfx/bus_sdio.c
+++ b/drivers/staging/wfx/bus_sdio.c
@@ -200,25 +200,23 @@ static int wfx_sdio_probe(struct sdio_func *func,
 	if (ret)
 		goto err0;
 
-	ret = wfx_sdio_irq_subscribe(bus);
-	if (ret)
-		goto err1;
-
 	bus->core = wfx_init_common(&func->dev, &wfx_sdio_pdata,
 				    &wfx_sdio_hwbus_ops, bus);
 	if (!bus->core) {
 		ret = -EIO;
-		goto err2;
+		goto err1;
 	}
 
+	ret = wfx_sdio_irq_subscribe(bus);
+	if (ret)
+		goto err1;
+
 	ret = wfx_probe(bus->core);
 	if (ret)
-		goto err3;
+		goto err2;
 
 	return 0;
 
-err3:
-	wfx_free_common(bus->core);
 err2:
 	wfx_sdio_irq_unsubscribe(bus);
 err1:
@@ -234,7 +232,6 @@ static void wfx_sdio_remove(struct sdio_func *func)
 	struct wfx_sdio_priv *bus = sdio_get_drvdata(func);
 
 	wfx_release(bus->core);
-	wfx_free_common(bus->core);
 	wfx_sdio_irq_unsubscribe(bus);
 	sdio_claim_host(func);
 	sdio_disable_func(func);
diff --git a/drivers/staging/wfx/bus_spi.c b/drivers/staging/wfx/bus_spi.c
index 40bc33035de2..605ad74068b7 100644
--- a/drivers/staging/wfx/bus_spi.c
+++ b/drivers/staging/wfx/bus_spi.c
@@ -154,6 +154,11 @@ static void wfx_spi_request_rx(struct work_struct *work)
 	wfx_bh_request_rx(bus->core);
 }
 
+static void wfx_flush_irq_work(void *w)
+{
+	flush_work(w);
+}
+
 static size_t wfx_spi_align_size(void *priv, size_t size)
 {
 	// Most of SPI controllers avoid DMA if buffer size is not 32bit aligned
@@ -207,22 +212,23 @@ static int wfx_spi_probe(struct spi_device *func)
 		udelay(2000);
 	}
 
-	ret = devm_request_irq(&func->dev, func->irq, wfx_spi_irq_handler,
-			       IRQF_TRIGGER_RISING, "wfx", bus);
-	if (ret)
-		return ret;
-
 	INIT_WORK(&bus->request_rx, wfx_spi_request_rx);
 	bus->core = wfx_init_common(&func->dev, &wfx_spi_pdata,
 				    &wfx_spi_hwbus_ops, bus);
 	if (!bus->core)
 		return -EIO;
 
-	ret = wfx_probe(bus->core);
+	ret = devm_add_action_or_reset(&func->dev, wfx_flush_irq_work,
+				       &bus->request_rx);
 	if (ret)
-		wfx_free_common(bus->core);
+		return ret;
 
-	return ret;
+	ret = devm_request_irq(&func->dev, func->irq, wfx_spi_irq_handler,
+			       IRQF_TRIGGER_RISING, "wfx", bus);
+	if (ret)
+		return ret;
+
+	return wfx_probe(bus->core);
 }
 
 static int wfx_spi_remove(struct spi_device *func)
@@ -230,11 +236,6 @@ static int wfx_spi_remove(struct spi_device *func)
 	struct wfx_spi_priv *bus = spi_get_drvdata(func);
 
 	wfx_release(bus->core);
-	wfx_free_common(bus->core);
-	// A few IRQ will be sent during device release. Hopefully, no IRQ
-	// should happen after wdev/wvif are released.
-	devm_free_irq(&func->dev, func->irq, bus);
-	flush_work(&bus->request_rx);
 	return 0;
 }
 
diff --git a/drivers/staging/wfx/main.c b/drivers/staging/wfx/main.c
index 84adad64fc30..76b2ff7fc7fe 100644
--- a/drivers/staging/wfx/main.c
+++ b/drivers/staging/wfx/main.c
@@ -262,6 +262,16 @@ static int wfx_send_pdata_pds(struct wfx_dev *wdev)
 	return ret;
 }
 
+static void wfx_free_common(void *data)
+{
+	struct wfx_dev *wdev = data;
+
+	mutex_destroy(&wdev->rx_stats_lock);
+	mutex_destroy(&wdev->conf_mutex);
+	wfx_tx_queues_deinit(wdev);
+	ieee80211_free_hw(wdev->hw);
+}
+
 struct wfx_dev *wfx_init_common(struct device *dev,
 				const struct wfx_platform_data *pdata,
 				const struct hwbus_ops *hwbus_ops,
@@ -332,17 +342,12 @@ struct wfx_dev *wfx_init_common(struct device *dev,
 	wfx_init_hif_cmd(&wdev->hif_cmd);
 	wfx_tx_queues_init(wdev);
 
+	if (devm_add_action_or_reset(dev, wfx_free_common, wdev))
+		return NULL;
+
 	return wdev;
 }
 
-void wfx_free_common(struct wfx_dev *wdev)
-{
-	mutex_destroy(&wdev->rx_stats_lock);
-	mutex_destroy(&wdev->conf_mutex);
-	wfx_tx_queues_deinit(wdev);
-	ieee80211_free_hw(wdev->hw);
-}
-
 int wfx_probe(struct wfx_dev *wdev)
 {
 	int i;
diff --git a/drivers/staging/wfx/main.h b/drivers/staging/wfx/main.h
index 875f8c227803..9c9410072def 100644
--- a/drivers/staging/wfx/main.h
+++ b/drivers/staging/wfx/main.h
@@ -34,7 +34,6 @@ struct wfx_dev *wfx_init_common(struct device *dev,
 				const struct wfx_platform_data *pdata,
 				const struct hwbus_ops *hwbus_ops,
 				void *hwbus_priv);
-void wfx_free_common(struct wfx_dev *wdev);
 
 int wfx_probe(struct wfx_dev *wdev);
 void wfx_release(struct wfx_dev *wdev);
-- 
2.20.1